If you look at yahoo latest earnings most of their money is coming from the Alibaba investment and their hedging of the yen, which seems to have been used to help pay for tumblr. Yahoo cannot buy their way out of this, just like steve jobs could not buy Apples way out during the 90's instead they had to use their human capital and innovate their way out. I don;t know who should have led yahoo but i do know that their biggest strength was their human capital which is being wasted and marginalized. It's even more evident when your competitors are implementing the research successfully and going further.